How To Choose The Right Solar Panels


Are you planning a photovoltaic system in 2022? Here you can find out everything about the production, efficiency and use of solar panels in your photovoltaic system so that you can make informed decisions!

Many solar panels are made from crystalline silicon. The chemical element silicon is the second most common element in nature after oxygen.

There is definitely enough silicon for future photovoltaic systems – the silicon deposits account for around a third of the weight of the earth’s surface! However, silicon is not found in its pure form, but bound as silicon dioxide (sand and quartz) or as a mineral (precious stones such as amethyst or opal).

1.How are solar panels constructed?

For industrial use as a semiconductor – such as in chip manufacture or for photovoltaic applications – the following happens:

The raw material quartz sand is freed from impurities and then converted into so-called metallurgical silicon with a crystal structure.

The solar silicon for PV solar panels has an even higher degree of purity than the silicon for computer chip production. You don’t really need to understand the principle behind the generation of solar power in the solar panels in order to use the many advantages of a solar system. Nevertheless, we would like to briefly point out that the physics of the solar solar panels can be understood relatively well even by laypeople. Of course, we could now overwhelm you with a long, boring text … but we’d rather keep it short.

And all this simply by video! The following contribution from “TheSimplePhysics, actually intended for physics tutoring, should offer enough explanation. And still in a fresh look.

For those who prefer to use the written word – here are some more key points on the subject of solar panels.

A solar solar panels consists of two layers of silicon.

An electric field is formed at the interfaces of the two layers.

Physical processes when exposed to light cause electric current to flow between metal contacts that are attached to these silicon layers.

There are different types that differ in purpose, performance and production of the silicon coating:

Monocrystalline silicon solar panels

Polycrystalline silicon solar panels

thin film solar panels

multiple solar panels

Organic solar panels

Up to now, mainly crystalline solar panels have been used in photovoltaic systems because their efficiency is usually higher. Above all, roof systems are almost always realized with crystalline solar panels.

1.1. Monocrystalline solar panels

The classic among the solar panels are the monocrystalline solar panels, which were already used in the first solar modules in space travel.

You can recognize the monocrystalline solar panels by their flat and smooth surface.

They look dark: anthracite, dark blue to black.

Silicon monocrystals, also known as single crystals, have an even arrangement of their atoms over the entire block of material.

They have an efficiency of 14 to 18 percent, which is slightly higher than the widespread multi-crystalline modules (12 to 16 percent).

The manufacturing process is very energy-intensive. This is why these solar panels are more expensive than their polycrystalline sisters. In fact, solar panel tax credit can greatly reduce the burden of installing solar systems, which can save us a lot of money.

1.2. Polycrystalline solar panels

More than half of the installed solar modules are composed of multicrystalline solar panels.

The efficiency is 2 percent lower than that of the monocrystalline solar panels

On the other hand, the production is more energy-efficient and the modules are therefore offered cheaper than the monocrystalline models.

You can recognize the multi- or polycrystalline solar panels by their characteristic, blue glittering appearance, which resembles ice crystals. This is because the silicon crystals are oriented differently in the solar panels. This enables you to recognize light and dark structures, depending on how the light hits the solar panels.

Unlike the monocrystalline process, the silicon melt is simply poured into blocks. After the block has hardened, it is cut into wafers. A simpler process that makes production cheaper. However, this results in relatively large, non-uniform crystals with visible grain boundaries.

Multicrystalline solar panels are also available in different colors, for example grey, green or gold. These “exotic” colors are used, for example, in the building integration of solar facades.

The disadvantage is that modules with these solar panels have a lower energy yield because of the lighter surfaces.

1.3. Thin film solar panels

As the name suggests, amorphous thin-film solar panels are about 100 times thinner than conventional, crystalline solar panels.

The semiconductor material silicon or other coating materials such as cadmium telluride (CDTe) or copper indium diselenide (CIS) is vapour-deposited or sprayed onto the carrier material (e.g. glass) in a thin layer. The layer thicknesses are less than 1 µm. For comparison: a human hair is about 50 to 100 µm thick.

Due to the small amount of material used, thin-film solar panels production is much cheaper than that of crystalline solar panels.

The use of thin-film solar panels is expected to result in a significant reduction in the price of photovoltaic systems in the long term.

The shares in the entire module market have increased disproportionately in recent years.

Thin-film modules are the future of PV modules. Inexpensive and flexible. If a plastic is used as the carrier material, flexible and bendable solar modules can be produced with it.

Applications today include backpacks, tents, outdoor clothing with amorphous silicon solar panels embedded in the fibres, power-generating membranes.

1.4. Organic solar panels

Instead of silicon, an organic solar solar panels consists of materials from organic chemistry – i.e. hydrocarbon compounds. The efficiency is currently still below that of conventional solar panels – but due to the following possibilities, intensive research is still being carried out on organic solar panels:

Favorable manufacturing costs – production is easier than with silicon solar panels

High current efficiencies – could be applied to or bonded to plastics

High flexibility

Possible transparency

High environmental compatibility

“Colourful” solar panels are possible

theoretically, a larger part of the solar spectrum can be used

2.What is the efficiency of solar panels

The efficiency or efficiency of solar panels is a very important criterion of solar panels. Simply put, the efficiency describes what percentage of the incident solar energy a solar solar panels can convert into electricity. You can use the solar power calculator to calculate how many solar panels you need to install to ensure your home’s daily electricity needs.

Photovoltaic efficiency describes the relationship between electrical power and sunlight

Many manufacturers and institutes are researching to further increase efficiency. And so there are always reports of broken solar panels efficiency records.

It should be noted that these records were achieved under test conditions in the laboratory and some of them are not used in series or are only used by space travel.

2.1. The future: multiple solar panels

With conventional solar panels, a large part of the light for power generation is lost on the back of the solar panels. solar panels stacked on top of each other can prevent this – or an intermediate layer on the back.

On the back, for example, a highly reflective layer – actually a mirror – can be applied. This sends back photons that had not previously produced any current in the semiconductor layer – and gives them a second chance, so to speak.

However, the multi-junction solar solar panels can then be integrated into photovoltaic modules in the normal way. The theoretically calculated limit of 29.4 percent for pure silicon solar panels can be further increased with this technology!

Here you will find out some background information on solar solar panels technology: Calculating the power of a solar panel, the “kWp value”, the various options for connecting solar modules and shading.

3.How does radiation & temperature affect the solar panels?

In general, the following applies, of course: the more sun that shines on the solar panels, the greater the electricity generated by solar panels.

The current increases in proportion to the intensity of the radiation (the voltage also increases somewhat).

Mathematically it looks like this:

Voltage (volts) x current (amps) = watts (power of solar panels)

The problem, however, is that as the temperature of the solar panels increases, the efficiency is reduced again.

If the rv solar panels or solar modules are cooled by wind and good ventilation (also dependent on the type of installation), these losses can be reduced.

Without ventilation, the losses are approx. 5% higher than with ventilation. At high temperatures you can specify about 0.5% reduction in performance per degree Celsius. If the temperature of a solar module increases from the recommended 25°C (according to the test conditions) to 55°C, for example, the module output drops by around 15%.

Those who are not particularly interested in the technology can safely switch off here and go to the next page. For all others:

3.1. How is the performance of a solar solar panels specified?

The output of a solar module is specified in watt peak (abbreviation: Wp) or kilowatt peak (abbreviation: kWp).

Did you know? The kWp value describes the optimal performance of solar modules under standardized test conditions (1000 W/m2 irradiation, 25 °C module temperature, 1.5 air mass). It therefore gives a standard value that makes solar modules comparable, not an average, minimum or maximum value.

If the sky is cloudy or if the solar panels heat up, the output of the solar generator is lower. In our latitudes, a 1 kWp photovoltaic system (equivalent to 7-8 m² module area) can generate around 800 to 1000 kWh of electricity per year (the higher values are achieved in southern US with optimal orientation).

The average annual power consumption of a four-person household in US is around 4,000 kWh.

4.Series and parallel connection of solar panels

The parallel connection is only briefly mentioned, but not actually used. When solar panels are connected in parallel, the voltage (volts) is the same across all solar panels, but the currents (amperes) add up to form a total current.

In the case of a series connection, on the other hand, the current is the same in all solar panels, but the voltage of the individual solar panels adds up to a total voltage.

Likewise, series vs parallel battery is actually not that complicated.

Although the topic also occurs in our area for the planning of photovoltaic systems, it also belongs here. If parts of the solar solar panels are in the shade, the yield of the entire module can drop because this part acts as a resistance in the circuit at that moment.

The solution here are so-called bypass diodes. The bypass diode directs the current past the shaded module. With older solar panels, a so-called hot spot can occur due to prolonged shading, which destroys the solar panels.